I want to know how to say, for example " I'm too busy to practice German". Would that be something like "ich bin zu beschäftigt zu Deutsch üben?". I would really appreciate it, sometimes I have a hard time making sense of german prepositions.
You can say either
Ich bin zu beschäftigt, um* Deutsch zu üben.
Ich bin zu beschäftigt zum Deutschüben. (Deutschüben = one word, nominalized)
The preposition is always zu. In the first alternative you don't have a mere infinitive, but an erweiterter Infinitiv beginning with um which is considered to be subclause-equivalent. In the second alternative, you have a nominalized verb (das Deutschüben), so it becomes a substantive preceeded by an article. Because the preposition zu requires the dative, the prepositional phrase originally would be zu dem Deutschüben. However, in this case zu dem always merges into zum.
*Without um, the sentence would read I'm too busy (with) learning German.
I'm too busy to practice German.
As already explained in other answers, both
Ich bin zu beschäftigt, um Deutsch zu üben.
Ich bin zu beschäftigt zum Deutschüben.
are acceptable ways to express the aforementioned statement.
However, note that both ways can be somewhat confusing because they could be interpreted differently: In both cases, the general sentence structure reflects the meaning of "in order to", that is, explaining the purpose of something. Outside of the "zu ... um zu" construction, "um zu" very uniquely means "in order to" in German.
As a native German speaker, I am regularly wary of using "zu ... um zu" for fear of being misunderstood, and generally try to circumnavigate this construction, for which there are several options:
- Only to be used in writing, and even there, it sounds rather old-fashioned:
Ich bin zu beschäftigt, als dass ich Deutsch üben könnte.
- More modern, and idiomatic both in written and spoken language:
Ich bin so beschäftigt, dass ich nicht/kein Deutsch üben kann.
- Also acceptable in all contexts, but switches the order in which information is given around:
Ich kann nicht/kein Deutsch üben. Dazu bin ich zu beschäftigt.